One-Step Polymerase Chain Reaction-Free Nanowire-Based Plasma Cell-Free DNA Assay to Detect EML4-ALK Fusion and to Monitor Resistance in Lung Cancer

A Poor Prognostic ALK Phenotype: A Review of Molecular Markers of Poor Prognosis in ALK Rearranged Nonsmall Cell Lung Cancer

BACKGROUND

Patients with nonsmall cell lung cancer with anaplastic lymphoma kinase (ALK) rearrangements derive a significant and durable clinical benefit from tyrosine kinase inhibitors (TKIs). However, early progression/death on treatment occurs in a subset of patients, which we term the poor prognostic ALK phenotype. This review aims to summarize the known molecular mechanisms that underlie this phenotype with a focus on variant 3 and TP53 mutations.

METHODS

A scoping review was performed using scientific databases such as Ovid Medline, Ovid Embase, and Cochrane Central Register of Controlled Trials. Studies included molecular markers of poor prognosis, with a focus on TP53 mutations, variant 3 re-arrangements, and poor clinical response to TKIs.

RESULTS

Of 4371 studies screened, 108 were included. Numerous studies implicated a negative prognostic role of variant 3, likely mediated through the acquisition of on-target resistance mutations and TP53 mutations which are associated with greater chromosomal instability and mutational burden. Co-occurring variant 3 and TP53 mutations were associated with even worse survival. Other mediators of early resistance development include aberrations in cell cycle regulators and mutations in cell signaling pathways. Comprehensive genomic analysis from first-line TKI clinical trial data was unable to identify a singular genomic signature that underlies the poor prognostic phenotype but implicated a combination of pathways.

CONCLUSIONS

This scoping review highlights that the poor prognostic ALK phenotype is likely composed of a heterogeneous variety of genomic factors. There remains an unmet need for a genomic assay to integrate these various molecular markers to predict this ALK phenotype.

Early On-Treatment Prediction of the Mechanisms of Acquired Resistance to EGFR Tyrosine Kinase Inhibitors

BACKGROUND

Prediction of resistance mechanisms for epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) remains challenging. Thus, we investigated whether resistant cancer cells that expand shortly after EGFR-TKI treatment would eventually cause the resistant phenotype.

METHODS

We generated two EGFR-mutant lung cancer cell lines resistant to gefitinib (PC9GR and HCC827GR). The parent cell lines were exposed to short-term treatment with gefitinib or paclitaxel and then were assessed for EGFR T790M mutation and C-MET expression. These experiments were repeated in vivo and in clinically relevant patient-derived cell (PDC) models. For validation in clinical cases, we measured these gene alterations in plasma circulating tumor DNA (ctDNA) before and 8 weeks after starting EGFR-TKIs in four patients with EGFR-mutant lung cancer.

RESULTS

T790M mutation was only detected in the PC9GR cells, whereas C-MET amplification was detected in the HCC827GR cells. The T790M mutation level significantly increased in PC9 cells after short-term treatment with gefitinib but not in the paclitaxel. C-MET mRNA expression was only significantly increased in gefitinib-treated HCC827 cells. We confirmed that the C-MET copy number in HCC827 cells that survived after short-term gefitinib treatment was significantly higher than that in dead HCC827 cells. These findings were reproduced in the in vivo and PDC models. An early on-treatment increase in the plasma ctDNA level of these gene alterations was correlated with the corresponding resistance mechanism to EGFR-TKIs, a finding that was confirmed in post-treatment tumor tissues.

CONCLUSIONS

Early on-treatment kinetics in resistance-related gene alterations may predict the final mechanism of EGFR-TKI resistance.

The impact of the ALK fusion variant on clinical outcomes in EML4-ALK patients with NSCLC: a systematic review and meta-analysis

Background: Recent studies showed that ALK-fusion variants are associated with heterogeneous clinical outcomes. However, contradictory conclusions have been drawn in other studies showing no correlation between ALK variants and prognoses. Methods: A systematic review and meta-analysis was performed to evaluate the prognostic value of EML4-ALK fusion variants for patient outcomes. Results: 28 studies were included in the analysis. According to the pooled results, patients harboring variant 1 showed equivalent progression-free survival (PFS) and overall survival (OS) with non-v1 patients (hazard ratio [HR] for PFS: 0.91 [0.68-1.21]; p = 0.499; OS: 1.12 [0.73-1.72]; p = 0.610). Similarly, patients with v3 showed the same disease progress as non-v3 patients (pooled HR for PFS = 1.07 [0.72-1.58]; p = 0.741). However, pooled results for OS suggested that patients with v3 had worse survival than non-v3 patients (HR = 3.44 [1.42-8.35]; p = 0.006). Conclusion: Results suggest that patients with v1 exhibited no significant difference from non-v1 in terms of OS and PFS, while v3 was associated with shorter OS in ALK-positive patients with non-small cell lung cancer.